Shrinkage of earth concrete amended with recycled aggregates and superplasticizer: Impact on mechanical properties and cracks

• Shrinkage of new raw earth concrete is affected by adding recycled concrete aggregates (RCA).
• Adding RCA reduces shrinkage kinetic and limit and increases the compressive strength.
• Vibration has an impact on pore diameter distribution.
• Superplasticizer reduces crack appearance but not the global shrinkage.

The study investigates shrinkage behaviour of a new earth concrete amended with various volume percentages of recycled concrete aggregates (RCA). Two preparations techniques, in situ (industrial) and laboratory (manual), were used. Shrinkage was evaluated using a one-dimensional method and a 2D image analysis. Shrinkage decreases with RCA percentages. Industrial vibration has also an impact on shrinkage. Adding superplasticizer reduces crack appearance without affecting the global shrinkage. Mechanical tests were performed to evaluate the impact of RCA. Compressive strength increases with the addition of RCA, and the bending tensile strength remains quasi constant.

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